For loops with itertools to count rows

Question

I have a .csv document with 16 rows. Each row starts with letters, in this case with a or b .

The outer for loop will check, line by line, the first letter. If row x starts with b , the second for-loop will count all rows until b occurs again.

Example:

1. a
2. a
3. a
4. a
5. b
6. a
7. a
8. a
9. a
10.a
11.a
12.a
13.b
14.a
…

b is found in line 5, next in row 13. There are 7 rows between…

That's my script to count rows from line 5 to line 13:

"Verschachtelteitertools"

import itertools
import re  
df = open('zeilen.csv')

for i, line in enumerate(df):
    #print(i,line)
    if re.search('b',line):
        #print(i,line)
        k = i+1
        count = 1
        #print(k)
        for line in itertools.islice(df,k):

            if bool(re.search('b',line)) == False:
                count=count+1
        lineX = count

print(lineX)

I have chosen itertools.islice() to count rows between b (1st occurrence) and b in line 13. k should represent the starting Point of the inner loop.

Answer 1

import itertools import re
df = open('zeilen.csv') for i, line in enumerate(df): #print(i,line) if re.search('b',line): #print(i,line) k = i+1 count = 1 #print(k) for line in itertools.islice(df,k):
if bool(re.search('b',line)) == False: count=count+1 lineX = count print(lineX)